1. Field of the Invention
This invention relates to a tension device and, more particularly, this invention employs state of the art technology together with a powerful D.C. motor to simulate the effect of the weight stack in an exercise machine.
2. Prior Art
Current muscle training machines can be divided into following two classes.
1. Spring load: As shown in FIG. 7, the winch 9A includes a spring as the means of generating a counterforce. When the cable 91 is pulled by the user interface, the disk 92 rotates and the spring 93 is wound. A counterforce proportional to the displacement of user interface is generated by the spring 93 accordingly. However, this counterforce cannot be controlled during the exercise.
2. Weight stack: As shown in FIG. 8, the system 9B includes a cable 91 and weight stack 94. As a force is applied on the cable 91, a counterforce due to gravity is produced by the weight blocks attached to the cable. This force can be varied by changing the number of the blocks manually. Nevertheless, to increase has to be interrupted increase or decrease the number of weight blocks.